Starting Point For Idle And Main Jets

[Hellion]

I've been eying the 6 or so inch long curved ones. Any advice or recommendation about that?

How much of a curve? There’s a few guys trying to run the U shaped ones (to where the carb is above the engine and out of harms way) but it does something funky to the A/F mix and the charge. Requires more tuning and Excedrin.

 

[Wicked_Daddy]

The issue with the curved manifolds is that they are 22mm. At least the one I have is. So it seemed a mismatch/waste to fit a 22mm manifold on a 24mm carb. The Nibbi manifold is made for the carb. That said, the intake port is about 20mm but the intake valve is 25mm. I ported my intake with a Dremel to match the manifold and taper it into the 20mm remaining distance to the valve. In theory, this would cause a venturi effect that will speed the flow of mixture into the chamber and provide the associated increased burn rate of the flame front for more complete combustion - thus my lean condition until I provided a richer mixture.

 

[OneTimeUser]

How much of a curve? There’s a few guys trying to run the U shaped ones (to where the carb is above the engine and out of harms way) but it does something funky to the A/F mix and the charge. Requires more tuning and Excedrin.

The ones I've been looking at are a bit less than 90 degrees and horizontal. "Some" say that the extra distance is better for atomizing and performance.

I'm over my head at this point 'cause I only understand the basics of carburetors.

 

[Whitetrashrocker]

Yes, long intake runners have better low end torque.

 

[panchothedog]

WTR,

You were spot on. I had leaks at both ends of my cheap Amazon manifold. The rubber gaskets are junk. I fixed one by tightening, but the other remains despite some torque and some gasket sealer.

It is better over all, but I'm now on the hunt for a new manifold.

I've been eying the 6 or so inch long curved ones. Any advice or recommendation about that?

Thanks again.

Yes. Don't buy the Amazon cheapie. We usually get what we pay for.